Here's an extract from the Owner's Manual for my 2012 Focus which should be similar:

Measure units
To toggle between metric and imperial
units, scroll to this display and press the
OK button.
Toggling the units of measure using this
display will affect the following displays:
• Distance to empty.
• Average fuel consumption.
• Instantaneous fuel consumption.
• Average speed.
Temperature units
To toggle between metric and imperial
units, scroll to this display and press the
OK button.
Toggling the temperature units using this
display will affect the following displays:
• Outside air temperature.
• The temperature display in the
automatic climate control.